1. Technical Field
The present invention relates to data center design and, more particularly to energy-efficient cooling systems in large data centers.
2. Description of the Related Art
Data centers are facilities that house numerous computer systems arranged in the form of electronics racks. Typically, a data center houses on the order thousands of electronic racks. Each computer system in a rack may include one or more processors, memory devices, controllers, power converters and manipulators, and other such electronic components. Depending upon the state of operation, a computer system may dissipate on the order of hundreds of Watts to thousands of Watts. Therefore, a significant amount of cooling is used to keep the electronic components within an optimum operating temperature range. Server driven power usage amounts to a significant portion of total US energy consumption. Liquid cooling solutions, which may include transferring 100% of the heat dissipated by the rack(s) to water, eliminating the facility air conditioning units, use of building chilled water to cool the racks, use of energy efficient chillers to provide relatively lower temperature coolants to the rack(s), and many other liquid cooling solutions, have been proposed as a means to reduce data center cooling/total power consumption. However, such solutions are far from optimal in their cooling energy efficiency.
Furthermore, many cooling systems are at least partially based on air cooling. Cool air is pumped into servers, cools auxiliary components, and exists as warmer air. A heat exchanger cools the air, which re-enters the server as cool air. Although liquid-cooled components can be overcooled, the temperature difference between coolant temperature entering the air heat exchanger and the air temperature leaving the air heat exchanger can become a limiting factor.